DE2208344A1 - Arrangement with several radiation sensors - Google Patents

Description

Patents Dlpl.-ln- '. Γ ", r" 'τ - *. sen, Dipi-i ι. . ; ht

052-18.381Ρ (18.382H) February 22, 1972

DYNARAD. Inc., Norwood (Mass.). V. St. A.

Arrangement with several radiation sensors

The invention relates to radiation sensors and
in particular to an arrangement for the electrical scanning of an observation area with an aligned radiation sensor.

The infrared radiation emitted by a body or an object has become an important source of information about this body or object. With the help of infrared sensors, the observation area along a or several vertical axes of the observation surface can scan the received from this observation surface infrared radiation in a series of electrical impulses which in turn are fed into a scoreboard can be, for example in a cathode

052-4 * NA-2) -Ko-r (7)

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beam tube to get an image of the received radiation to create.

The scanning can be done with the help of a single probe be carried out that mechanically scans or that has an optical path that is mechanically along one or more Axes. However, the mechanics of such scanning devices are often expensive, sensitive and tend to be to be slow in their scanning speed. Instead of of this, an ordered or extended arrangement of sensor cells can also be used, with mechanical or electrical devices sequentially or in order detect or scan the radiation value incident on each cell of the arrangement »mechanical scanning devices for such an arrangement tend to be noisy or noisy electrically and mechanically. Your operational safety is small and they are sensitive to movement. Electronic scanning devices from conventional ones Construction create destructive switching transitions. They often require complicated and unstable voltage references. Finally, they are determined by the time constant of the individual sensors and circuits over short sampling intervals restricted.

In a preferred embodiment of the invention, a scanning device is provided which is repetitive or a sequence of pulses is periodically generated, the position of which is modulated in such a way that it is in the actual time with an infrared or another radiation that focuses on an array of sensor sources is to The position of each pulse represents the amount of radiation which falls on a corresponding cell of the arrangement "

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~ 3 -

The electronic scanning of the cell arrangement for generating the pulse train is achieved in that a Ramp signal is fed into series-connected circuits and pulse generators, with each sensor cell part of a corresponding circuit is. The resistance Each sensor cell is changed depending on the size of the radiation incident on it. «Each cell works in of each circuit in such a way that the potential or the charge on a capacitor of the circuit is consistent with that of the circuit Resistance of the cell changed «Each capacitor of the circuit is charged during a rise time of the ramp signal, which is fed into this circuit above a reference level, which is preferably zero. «Each capacitor is optionally fed in according to the assigned cell resistance during part of the Ramp signal that is below this reference level is discharged. The subtraction of the capacitor potential from the injected Ramp Level produces a signal that crosses the reference level in a time that represents the cell resistance and corresponds to the incident radiation o The ramp signal fed into each circuit is combined offset by an average signal level contributed by each circuit of the interconnected circuits so that a separate and unique time domain for the crossing level is established by each circuit is.

With the aid of a ramp signal and the common offsets, electronic sampling becomes without the difficulty the switching surges and the changes in the reference voltage. Since the ramp signal has a long

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rehabilitate frequency than the detection frequency of the sensor, the sensor time constants are nowhere near any Restriction of the sensor acquisition speed.

The pulse train can be converted into a signal with a variable amplitude that is used to control the Display intensity on a display screen is used to generate a light intensity pattern in which locally the radiation intensity received by the sensor arrangement is displayed. The arrangement can also be rotated mechanically to a solid angle range for the detected To deliver radiation, which in turn is displayed as a two-dimensional light pattern on the display screen can.

The invention is explained in more detail below with reference to the figures. Show it:

Fig. 1 is a block diagram to explain the general Mode of operation of the invention;

2 shows a diagram with the electronic devices according to the invention Scanners j

Fig. 3 is a waveform diagram useful for explanation the electronic scanning according to the invention is used;

Fig. 4 is a waveform diagram showing the conversion of the

pulse position modulated signal into an amplitude modulated Signal explained;

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Fig «, 5 a circuit of a form of embodiment of the sensor line circuit;

6 shows a circuit of a further embodiment the sensor cell circuit;

Fig. 7 is a block diagram of a modified scanner; and

8 shows a diagram of a scanning device according to the invention with a solid angle of ₀

In FIG. 1, a substrate 12 has a linear array 13 of sensor cells lh and corresponding series-connected circuits 16 and pulse generators 18 _o A ramp generator 19 supplies a periodic ramp signal in the series connection of the circuits 16 a. A circuit 16 and a pulse generator 18 operate with each sensor cell 1 * f in order to enable successive scanning of each sensor cell and to generate a pulse position-modulated pulse sequence as a function of the ramp signal. The position of each pulse represents the radiation incident on a corresponding sensor cell.

In the preferred embodiment, each sensor cell Ik responds to infrared radiation from a source which is linearly offset from the radiation sources of the remaining cells 14 of the arrangement 13. The arrangement of the cells and the spectral sensitivity of the cells are only examples. The arrangement of the cells and the spectral sensitivity of the cells can be adapted to the respective requirements.

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In FIG. 2, the electronic devices provided on the substrate 12 for carrying out the electronic scanning of the arrangement 13 are shown. A plurality of circuits 20, which have inputs 22, outputs 24 and ground points 26 , are provided on substrate 12.

Each circuit consists of a resistor 28 which connects the input 22 to the positive or hot side of a capacitor 30, while the negative or cold side of the capacitor 30 is connected to the ground terminal 26. In each circuit, a parallel connection of a variable resistor 32, a sensor cell 3k and a sliding capacitor 26 leads from the connection point of the resistor 28 and the capacitor 30 to the anode of a diode 380.The cathode of the diode 38 is connected to the output 24 of each circuit 20. All of the circuits 20 are connected to one another in series in such a way that the output 2k of one circuit is fed directly into the input 22 of the next following circuit on the substrate 12. Successive circuits 20 include successive sensor cells 34 in the linear array of cells.

The output 2k of each circuit leads to pulse generators 39, each of which has two resistors k0 and k2 as a voltage divider, the resistor k2 leading to the ground point 26. The connection point between the resistors k0 and 42 is connected to the base of an npn transistor kk , the emitter of this transistor kk being grounded. A resistor 46 connects the collector of transistor 44 to a supply line 48 of positive voltage. The collector of transistor 44 is over

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an output capacitor 50 is alternately coupled to the base of a transistor 52, the transistor 52 being biased by voltage-dividing resistors 54 and 56, which are each connected to the positive supply line 48 and the ground point 26. An emitter resistor 58 connects the emitter of the npn transistor 52 to ground terminal 26, while a collector resistor 60 connects the collector of transistor 58 to positive supply line 48. An output capacitor 62 generates an alternating coupling and differentiation of the signal at the collector of transistor 52 and feeds this signal into the base of a pnp -Transistor 64, the emitter of which is connected to the positive supply line 48. The collector of the transistor 64 is connected to the ground line 2, 6 via a resistor 66 , while the base is connected to the ground line 26 via a resistor 68. The transistor 6h acts as a pulse-shaping transistor and generates an output signal via a capacitor 70 which is connected to the collector of the transistor 6h . The outputs of the capacitors 70 are all connected to a pulse train conductor 72 which leads to a pulse amplifier 74 «

An indicator 76 in the form of a cathode ray tube has a terminal 78 for the horizontal time deflection, which is for a sawtooth ramp signal with a time deflection rate is set to about 2 kHz. The ramp signal from this terminal is fed into input 22 the first circuit 20 of the series-connected circuits.

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As an example, values for the important components of the circuit 20 and the pulse generator are shown below in a table 39 stated:

Component value

Sensor Jk between 30 kQ and kO

Capacitor "} 6 between 0.01 and 1.0 /

Resistance 28 2 k / 2

Capacitor 30 1.0 / uF

Ramp signal 2 kHz with an output impedance

from 2-10 H

Resistances kO and k2 each 100 kilograms

In operation, the periodic ramp signal of a frequency of 2 kHz from output 78 is an alternating current signal which bridges the zero signal level established by the level of the ground line 26. This signal is fed into the first circuit 20 and low-pass filtered by the combination of the resistor 28 and the capacitor 30. Diode J8 does not conduct until the ramp signal becomes positive by an amount that exceeds any residual voltage on capacitor 36 that is in parallel with sensor cell 3k. The residual voltage on capacitor 36 is determined by the resistance of cell Jk , which discharges capacitor 36 during the negative parts of the ramp. It is charged by the voltage across it during the positive parts of the ramp. In this way, the voltage at the output Zk of the first circuit 20 exceeds the value zero in a time which depends on the charge of the capacitor 36 and correspondingly on the resistance of the sensor cell 3k. Because the resistance

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of the cell depends on the radiation incident on it, represents the time, in relation to the time in which the ramp signal of 2 kHz crosses the value zero, in which a positive voltage first occurs at the output 2k of the first circuit that acts on the sensor cell in this first circuit represent incident radiation. As soon as the output signal 2k becomes positive, the transistors kk , 52 and 6k cause amplification, differentiation and saturation shaping, in order to generate a well-shaped pulse at the output of the capacitor 70 »The occurrence of the pulse is delayed by the time in which the voltage on the capacitor 30 first becomes positive by an amount which depends on the radiation incident on the corresponding sensor cell 3k.

The output 2k of the first circuit 20 is connected to the input 22 of the second circuit 20. The second circuit low pass filter formed by resistor 28 and capacitor 30 receives the ramp signal through the AC coupling of capacitor 36 in the first circuit. The low-pass filter is equipped with a very low time constant in order to filter out all transient and short-term charges. When discharging, only an average voltage is obtained, which is shifted by the capacitor of the first circuit. This shift is in the negative direction and is added to a further short voltage shift that is brought about by the capacitor 36 in the second circuit 20. The pulse finally generated by the second pulse generator 39 at the output of the capacitor 70 is delayed by a time which corresponds to the mean displacement plus a time.

2 0 0 «0 8 / Ci 7 0 ö

speaks, which represents the radiation incident on the FUhJ erzeile 3k of the second circuit. A few periods of the ramp signal are required to run in before the entire circuit is in the idle state.

There are so many additional similar pipeline networks and appropriate circuits are provided, such as sensor cells 3 ^ in of the arrangement 13 are desired. While the basic structure every line network is the same, the values of the Components differ slightly, with the mean displacement of each line network being essentially the same having. The variable resistors 3 ^ are provided to this set the mean shift.

3 shows a series of curves 80, 82, 8k, 86 and 88 following one another in time, which correspond to the line networks and the pulse generators from the Nth to the N + ^ th sensor cell in FIG. The curves represent ramp signals as observed at different points in a sequence of five adjacent circuits. The various circuit points at which the illustrated waveforms occur are designated by 90, 92 and 9k and correspond to the signals at the inputs 22 after the low-pass filtering, the signals at the outputs 2k after amplification and the pulse-shaped output signals at the capacitors 70. The The result of the summation of all these output signals of the capacitors 70 in the line 72 produces a pulse train which is designated by 96 .

As shown in Fig. 2, the sawtooth is

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gnal is fed at a frequency of 2 kHz from terminal 78 to a synchronized sawtooth generator 100 which operates at a much higher frequency than 2 kHz. The period of this high sawtooth frequency is calibrated to compensate for the period of the pulses aTif of the line 72 train when all the sensor cells are receiving the same radiation. The outputs of the pulse amplifier 7h and the synchronized ramp generator 100 are fed into a Videodiskriminator 102 which modulates the output pulse train of the pulse amplifier "7k in amplitude. As seen from Fig k apparent., The modulation is effected in that the amplified pulse train at the output of the synchronized sawtooth generator 100 is added and that a sufficiently negative bias voltage is added so that the resulting signal only exceeds the zero level signal when a pulse from the amplifier 7 ^ occurs _c After the rectification of the positive half cycle in the video discriminator 102, the resulting output pulses have an amplitude which is relatively dependent on the occurrence of each period of the sawtooth output signal with respect to time u modulate.

Various changes can be made in circuit 20 to provide increased sensitivity to changes in the resistance of the sensor cell. This is especially true for low levels of incident radiation and accordingly for high values of the resistance of the sensor cell. Such a modification is shown in FIG. It is above the entrance Wk

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In the circuit, a resistor 110 and a capacitor 112 are provided as a low-pass filter. From the connection point between the resistor 110 and the capacitor 112 leads a sliding capacitor 116 to the anode of a diode 118, which is in a Forward direction connected to an output 120 of the circuit is. An npn transistor 122 with its emitter and its collector is located above the sliding capacitor 116, wherein the emitter is connected to the low-pass filter. A power source or power supply 124 for transistor 122 is connected to the collector via resistors 126 and 128, respectively and connected to the emitter. A voltage divider via the power supply unit 124, which consists of a resistor 130 and a sensor cell 132 is fed a current. Call at this circuit Changes in resistance of the sensor cell 132 in the control changes with respect to transistor 122, with the resulting gain being passed on to capacitor 116 gives the gain of transistor 122.

In Fig. 6 is another, similar to Fig. 5, but a somewhat simplified modification is shown. The power source or power supply unit 124 is omitted. Here is the Capacitor 116 connected to the transistor circuit connected to which the power supply unit or the power source 124 was provided in FIG. 5. The connections between the capacitor 116 directly to the emitter and collector of transistor 122 are omitted. In the exemplary embodiment 6, the charge on the capacitor ensures the source of operation for the transistor circuit, with the mode of operation corresponds in all other points to that of the embodiment s of FIG. 5 to gain

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the changes in resistance of cell 132 upon discharge of the capacitor 116 to cause. The transistor 122 ensures a reduced resistance discharge path for capacitor 116 under the control of the higher resistance in cell 132.

As has already been explained above, the device shown in FIG. 2 with the circuits of FIGS. 1, k or 5 causes a common reduction in the potential of the ramp signal from one circuit 20 to the next during operation. This joint decrease in turn actually causes a time shift from one circuit to the next at the point when the ramp signal crosses the zero level associated with each circuit. This mutual shift and the resulting time shift produce the effect of electronically scanning the values of the sensor cells in a linear array. In Fig. 7, a further embodiment for this electronic scanning is shown. This embodiment comprises a ramp generator 13 which feeds a ramp signal into a circuit 1 36 of a first sensor cell and also into a DC shift circuit 138. The circuit 138 contains, for example, a filtered zener diode or a battery. Circuit 138 subtracts a predetermined constant DC level from the ramp signal generated by generator 13 ^. The output of circuit 138 is fed to a circuit 1 kO of a second sensor cell and a second DC shift circuit 1 ^ 2. The circuit 142 ensures a corresponding direct current reduction of the signal coming from the Rainpen generator 13 ^. This arrangement is repeated over as many DC shifter circuits and circuits as there are

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is required to match the number of sensor cells in the to adapt to the linear arrangement. The entire system generates an electronic scan of the arrangement of the sensor cells, which results in a pulse train which deviates from a constant distance by amounts that are applied to each cell incident radiation are characteristic.

The circuit causing this direct current shift can comprise only one resistor, so that the series of circuits causing a direct current shift forms a voltage divider system via the output of the ramp generator. In this case, the ramp generator acts as a current source at its outputs, the voltage amplitude corresponding to the ramp signal. It is important in these modified or alternative systems that the voltage swing of any circuit based on the detected radiation not exceed the DC offset between the circuits. In the embodiment of FIG. 2, this is automatically ensured by the effect of the displacement of the capacitor.

A complete radiation detection device with the scanning system according to the invention is shown schematically in FIG. The device comprises a housing } kk with an opening 148. In the housing 1hk and behind the opening 1U8, a substrate 150 is mounted on pivot pins 152 and 15 ^ for rotation about an axis 156. The substrate 150 contains a linear array 158 of sensor cells. Line networks 160 and pulse generators 162 are provided next to the cells of the sensor arrangement 158 on the same substrate.

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. _15th 22083U

Subsirate 150 is connected to an infrared lens in opening 148 via a support ~ \ 6k. An optical axis 168 of lens I66 traverses approximately the center of array 158 of sensor cells. The lens 166 is curved out of the opening 1 ^ 8 towards an observation surface 170. An edge of the lens 166 is pressed against a nook or a lifting thumb 172 which rotates about an axis 17 ^ parallel to the axis 156. One rotation of the cam 172
causes lens 166 to go up and down about axis 156, thus changing the angle pointed to by optical axis 168 of lens I66.

The support * \ 6k is designed for a sliding movement of the substrate 150 with respect to the lens 166 in order to adjust the focusing of the radiation on the arrangement I58. Since the array I58 of the sensor cells is actually a single row of cells, the radiation received by the lens 166 is focused on the sensor cells over a one-dimensional angle of the observation surface 38 is, this angle sweeps over a perpendicular angle of the observation surface 38 to effect the scanning of a right-angled solid angle.

A vertical time base terminal 176 is provided on the indicator 76 and set to a low frequency (e.g., 20 Hz) of a sawtooth signal. This connection I76 additionally controls the vertical deflection of the beam on the display screen IO6 and is also connected to a motor 178 which operates synchronously at 20 Hz to drive the cam 172 of FIG.

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on the other hand, the oscillation of the lens 166 over the axis 156 with a frequency of 20 Hz.

The indicator I76 is fitted into the housing 1UU (shown schematically in FIG. 8), and its display screen 106 points into a chamber I80 which is provided perpendicular to the optical axis 182 of a converging lens 184. At an angle of 45 ° to the optical axis 182, a reflective surface I86 is provided behind the lens 18k, which reflects the illumination from the display screen IO6 onto a camera I88 with a film plane 190. The film plane 190 carries a film 192, which is stretched between an unwinding and winding roller 19k and 196, respectively. Lens I8U is adjusted to focus the image from display screen 106 onto film 192. The camera can be provided with a conventional mechanical shutter (not shown). The indicator 76 can also be designed in a conventional manner so that an indication occurs at predetermined time intervals, the film 192 being exposed in this predetermined manner.

Instead of the specified frequencies and periods for the ramp and sawtooth signals can also be significantly different frequencies and periods can be used. Other circuits and mechanical devices can also be used be provided. In particular, the arrangement need not be a straight line of sensor cells, but can comprise some predetermined pattern of cells. The sensor cells can also be exposed to radiation other than the infrared, for example to the visible radiation, be sensitive. But you can also do any be variable line facility.

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Claims (1)

Claims ^ 1 J Arrangement for the successive scanning of several radiation sensors in order to generate a sequence of signals which represent the radiation incident on the corresponding sensor, marked by a first device (19) for generating a periodic electrical output signal, which has a part with a continuous having increasing signal level, a plurality of signal shifting circuits (z. B. 20) which are connected in series to receive the output signal of the first device (19) for generating a periodic electrical signal and which generate a signal at the output of each signal shifting circuit, the signal level of which is together smaller as the output signal of the first device (19) for generating a periodic electrical signal, this being determined by the position of each shift circuit in its series connection, a second device assigned to each shift circuit (e.g. 20) and each sensor (1h, 3k) for storing a signal with ei ner first speed when the output signal of the associated circuit (20) is above a predetermined signal level, and for reducing the stored signal at a speed that the radiation incident on the associated sensor (i4, 34) during other parts of the output signal of the associated circuit reproduces, each second means for storing a signal generating an output signal which is the output signal of the associated circuit (20) shifted by an amount equal to that on the second means for storing a 209838/0706 Signal reproduces stored signal, each signal storage device associated third device (36) for Generating a signal in a time which corresponds to the time when the output signal of the associated signal storage device exceeds a predetermined signal level, and fourth means (72) for combining of the signals generated in this way in order to generate a signal sequence which corresponds to the Radiation. 2. Arrangement according to claim 1, characterized in that the plurality of series-connected circuits (20) a resistive voltage divider (40, 42), wherein the connection point between two adjacent resistance elements of the voltage divider is the output signal generate each circuit, and that the first means (19) for generating a signal is essentially one uniform current in the series connection of the circuits (20) feeds, whereby a change in the potential in the end points of the series circuit corresponds to the periodic electrical Signal corresponds. 3. Arrangement according to claim 1 or 2, characterized in that the signal shifting circuit comprises a low-pass filter (28, 30), that the means for storing a signal comprises: a capacitor (36), wherein the associated sensor is connected in parallel with the capacitor, a Diode (38), a resistor (3 * 0), the capacitor receiving the output signal of the associated low-pass filter (28, 30) at one terminal and feeding the signal at the other terminal into one terminal of the diode (38), where- 209B38 / 0706 at the other terminal of the diode, the output signal of the circuit is generated and is connected to a reference level via the resistor, that the first device (19) for generating a signal comprises several pulse generators (39), associated with a corresponding circuit (20) for generating an output pulse when the output signal the circuit crosses the predetermined signal level, and that means (72) for summing the output signals is provided by each of the multiple pulse generators, to generate the signal sequence that reproduces the radiation incident on the corresponding sensor. H. Arrangement according to claim 3 t characterized by several devices (z. B. 122) for amplifying the response of each sensor {lh, 3 ^) to the incident radiation in order to achieve a greater change in the rate of fall of the signal stored by the capacitor with the change in the to ensure incident radiation on the associated sensor (Fig. 5) 5. Arrangement according to claim k _t, characterized in that the devices for amplifying the response of each sensor comprise a solid-state amplifier (ζ. Β. 122) which has a control connection which is controlled by the change in the associated sensor, depending on that on these incident radiation, and which has controlled conductor terminals connected in a path to cause the drop in the signal stored by the associated capacitor. 209838/0706 22083U 6. Arrangement according to claim 1, characterized by a substrate (150) which carries a linear arrangement of the sensors (158), means ('[6k) for deflecting the radiation from a viewing angle onto the linear arrangement of the sensors, a device (i68, 172) for scanning the steering device in order to have the viewing angle repeatedly swept over a solid angle for the radiation incident on the sensor, and to generate a series of signal sequences, each signal sequence referring to the linear arrangement of the sensors under a viewing angle reproduces incident radiation which is shifted in the direction of the sweep with respect to the viewing angle for the immediately preceding signal sequence (FIG. 8). 7. Arrangement according to claim 1, characterized by means (70, 72) for combining the signals of the signal trains into a pulse train, each pulse coinciding is modulated in its pulse position with the radiation incident on the corresponding sensor, a device (102) to convert the pulse sequence of the pulses modulated in their pulse position into an amplitude-modulated signal, and an indicator (76) which, depending on the amplitude-modulated signal, generates a light pattern that is in its Intensity is modulated at points that reflect the position and size of the radiation incident on the sensor. 8. Arrangement according to claim 7 »characterized in that that the devices for converting the pulse train comprise: a device (100) for generating a sawtooth signal, where each rising part of the sawtooth signal is able to match the range of expected positions for a corresponding 209838/0706 speaking impulse coincides in the impulse sequence, one Means (102) for summing the sawtooth signal and the pulse train to generate a sum signal, means, to cut off the sum signal at a clipping level that cuts out all the parts of the sum signal, except for the parts that are ascribable to the pulse train, and a device (10 ^) for G smoothing of the clipped signal to the amplitude-modulated Generate signal. 209838/0706